Mosaic screen structure



June 7, 1938. H A. [AMS 2,120,099

MOSAIC SCREEN STRUCTURE original Filed March so, 1953 i Patented June 7, 1938 l vUNITED lSTATES- PATENT OFFICE MOSAIC SCREEN STRUCTURE Harley A. Iams, Berkley Heights, N. J., assignor to Radio Corporation of America, a corpora.- tion of Delaware Application March 30, 1933, Serial No. 663,451 Renewed August 21, 1936 Claims. (Cl. Z50-27.5)

My invention relates -to improvements in the final steps in the making of the tube. Many methods of making mosaic screen structure, and diierent types of screen structure have been particularly to such structure fo'r embodiment proposed, but each ofthese, has been found to in a cathode ray tube for television transmishave at least one disadvantage to prevent it 5 sion. from meeting all of the requirements referred to.

One form of cathode ray tube for television With the foregoing 'in mind, it is one ofthe transmission comprises screen structure made objects of my invention to provide an improved of a sheet of insulating material over one surmethod of making mosaic structure of the charface of which is disposedA a great number of acter referred to whereby all the requirements 10 individual elements of electrically-conductive for satisfactory operation and manufacture are l matrial, such as silver. These elements are met. spaced with respect to each other, andeach In accordance with my invention, asubstanis photosensitized. In operation, a light image tially continuous layer of electrically-conductive of the object ls projected onto the photosensimaterial is applied to one side of a sheet of intive, mosaic surface to develop an electrical sulating material. 'I'his layer is then ruled with 1J image of the object in the form of individual a sharp-edged instrument along two sets of parelectrostatic charges on the respective elements allel lines, the lines of one set being disposed at which correspond in magnitude lto the respecany desirable angle to those of the other set. tive and corresponding values of light intensity In thisway, minute parallelograms are engraved at they elemental areas over the object. The on the surface and constitute the individual ele- 20 tube is provided with means for developing a ments required. cathode ray and directing it onto the photo- My invention resides in the improved method sensitive, mosaic surface, which ray is deflected of the character hereinafter described and in a predetermined manner fdr scanning. Durclaimed. 1

ing the scanning action, the electrostatic charges For the purpose of illustrating my invention, 5 referred to are successively neutralized to dean,embodiment thereof is shown in the'drawing, velop picture signals for transmission. wherein With regard to the construction of satisfacl Figure 1 is a simpliiled elevational view, parttory mosaic screen structure for-the above purly diagrammatic, of apparatus embodying my pose, the requirements are suchas to give rise invention; 30

to diillcult problems. For example, if suicient Fig. 2 is an enlarged sectional view, illustratdetail of the transmitted object is to be reproing one step in my improved method;

duced at the receiving points, the number of Fig. 3 is an enlarged fragmentary view, illusthe individual elements over the screen surface trating another step in my improved method;

should be of the order of 10,000 per square inch, and 3:, and the size and spacing should be such that Fig. i is a sectional view, the section being the correct capacities will be obtained to handle taken on the line 4-4 in Fig. 3. the electrostatic charges referred to. Further- With reference to Fig. .1, the numeral I0 desmore, the construction must be such that pracignates my improved screen structure embodied tically no leakage can take' place between adia- -in a cathode ray tube I2. The tube is provided 4o cent elements. Otherwise, the electrostatic with suitable means I4, in the form of a gun, .charges accumulated will leak away, at least for developing a ray I6 of electrons whichjs. partially, before being scanned and discharged directed at the photosensitivepmosaic surface I8 by the ray. 'I'his undesirable leakage action of the screen I0. In operation, an image of the interferes with fidelity of picture reproduction object 20 is projected by a suitable lens system 45 atl the receiving points. 22 onto the surface I8.A

Another important consideration in the con- The ray I6 is caused to scan the surface I6 struction of the mosaic screen resides in the by coils 24 which operate to deflect the ray horinature of the steps for making the tube. For zontally, and by coils 26 which operate to deflect example, one of these steps consists in the bakthe ray vertically. The picture signals developed 50 ing of the tube ata relatively high temperain the output line 28 from the tube are ampliiled ture. The temperature is so high that there is and transmitted by suitable apparatus 30.

a limitation on the construction and materials With reference to Figs. 2, 3 and 4, my imused for making the screen structure. Otherproved screen structure is`made by taking a Y wise. this structure would be destroyed during mica sheet 32 and applying to one surface there- 55 of a thin and continuous layer ll of silver. A continuous coating 3l of platinum is applied to the other side of the mica sheet. In operation, the connection 2l is made to the layer 38.

Satisfactory screen structure has been made by using a mica sheet about 1/1000" thick, and by making the thickness of the silver layer 34 of the order of 1/10,000" thick. These values are not critical in any strict sense of the word, and may be varied over a relatively wide range to suit particular requirements.

The silver layer Il is then ruled with a suitable sharp-edged instrument along two sets of parallel, evenly-spaced lines. wherein the lines of one set are preferably, though not necessarily perpendicular to those of the other set. This makes the square silver elements 3.a, as shown in Fig. 3, each of which is later photosensitized. In the ruling operation, the edge of the instrument is made to cut entirely through the silver layer 34 and slightly into the mica sheet 32, so that there is assurance that the insulating material will be laid bare between the elements 34a. Another advantage of this method is that the leakage path between the adjacent elements 34a, measured along the surface of the mica, is greater than the distance between the adjacent elements. With regard to the ruling step, satisfactory results have been obtained by making the number of lines in each set equal to 100 per inch.

From the foregoing, it will be seen that I have provided an improved method of making a mosaic screen structure wherein the individual elements of electrically-conductive material are formed by first applying a layer of this material to one surface of an insulating sheet, and then by removing some of the electrically-conductive material to lay bare the insulating material between the respective elements and thereby form the latter.

I claim as my invention:

1. A light sensitive screen structure comprising a sheet of insulating material provided on a surface thereof with a mosaic in the form of a plurality of individual light sensitive elements oi' electrically-conductive material leach insulated and spaced from each other, the leakage path between the respective adjacent elements measured along the intervening insulating surface being greater than the distance between such elements.

2. A screen structure comprising a sheet of insulating material provided on a surface thereof with a layer of electrically-conductive light sensitive material having intersecting grooves therethrough forming over said surface a mosaic comprising a plurality of individual elements ofthe electrically-conductive material each insulated from the others by the insulating material of said sheet, said sheet being provided on the other surface` thereof with a. 'layer of electrically-conductive material insulated from each of said elements by the insulating material of said sheet and providing an operating electrode common with respect `to said elements and which constitutes, with each of said elements and the intervening insulating material of said sheet. a condenser.

3. Screen structure comprising a sheet of. insulating material provided on a surface thereof with electrically-conductive material intersecting grooves therethrough to form over said surface a mosaic comprising a plurality of individual elements of the electrically-conductive material each, insulated from the others by the insulating material of said sheet, said elements having being photosensitive, said sheet being provided on the other side thereof with a layer of elect-rically-conductive material insulated from each of said elements by the insulating material of said sheet and providing an operating electrode common with respect to said elements and which constitutes, with each of. said elements and the intervening insulating material of lsaid'sheet. a

condenser.

4. Screen structure comprising a sheet of insulating material provided on a surface thereof with a layer of electrically-conductive material having therethrough two sets of parallel groo'ves 1 intersecting to form l'over said surface a mosaic comprising a plurality of individual elements of the electrically-conductive material each insulated from the others bythe insulating material of said sheet and'being in number at least of the order of. ten thousand to the square inch, said sheet being provided on the other side thereof with a layer of electrically-conductive material insulated from each of said elements by the insulating material of said sheet and providing an operating electrode common with respect to said elements and which constitutes, with each of said elements and the intervening insulating material of said sheet, a condenser. i

5. Screen structureA comprising a sheet of* insulating material whose thickness is of the order of one one-thousandth of an inch and vwhich is provided on a surface thereof with a layerfof electrically-conductivel material whose thickness is of the order of one ten-thousandth of an inch and which has therethrough two sets of parallel grooves intersecting to form over said surface a mosaic comprising a plurality of individual elements of the electrically-conductive material eachv mon with respect to said elements and which constitutes with each of said elements and the intervening .insulating material of said sheet, a condenser.

6'. 'I'he method of preparing/a mosaic electrode which comprises coating one `side of a non-conductingbase with a continuous film-of conducting material, scoring the conducting material valong a plurality of predetermined intersecting paths to remove completely from the insulating base the scored conducting material and to -provide thereby a mosaic structure of minute-size conducting areas supported in an electrically iso?, lated manner upon the non-conducting base, and

coating the opposite side of the non-conducting base with a continuous film of conducting material.

'1. The method of preparing amosaic electrode which comprises coating one side of a non-conducting base-Awith a continuous illm of conducting material, scoring the conducting material along a pluralityof predetermined intersecting paths to remove completely from the insulating base the scored conducting material and to provide thereby a mosaic structure o f minute-size conducting areas supported in an electrically'isolated manner upon the pont-conducting base,

coating the opposite side of the non-conducting base with a continuous film of conducting material, positioning the formed mosaic structure within a tube blank, evacuating the tube blank, oxidizing the isolated conducting areas formed on one side of the non-conducting support member, and photosensitizing the oxidized isolated conducting areas only.

8. The method of preparing a mosaic electrode which comprises coating one side of a non-conducting base with a continuous lm of conducting material, simultaneously scoring the conducting material and the insulating base to a predetermined depth along a plurality of predetermined intersecting paths to remove completely from the insulating base the! scored conducting material and to provide thereby a mosaic structure of minute-size conducting areas supported in an electrically isolated manner upon the nonconducting base, and coating the opposite side of the non-conducting base with a continuous film of conducting material.

9. The method of preparing a mosaic electrode which comprises coating one side of a non-conducting base with a continuous film of conductducting base, coating the opposite side of theY non-conducting base with a. continuous film of conducting material, positioning the formed mosaic structure within a tube blank,'evacuating the tube blank, oxidizing the isolated conducting areas formed on the non-conducting support member, and photosensitizing only the isolated conducting areas.

10. The method of preparing a mosaic electrode which comprises coating one side of a non-conducting base with a continuous illm of conducting material, producing isolated discrete oxidized metallic particles according to a predetermined pattern on the opposite side of the non-conducting base, and subsequently photosensitizing said oxidized particles.

HARLEY A. IAMS. 

